This invention relates to air treatment in air circulation systems and, more particularly, to a disposable envelope or packet which contains a quantity of air freshening material. The envelope may be easily attached to any one of a number of different types of air filters customarily used in air circulation systems, or to other points inside the air circulation conduit system.
In both residential and commercial structures, there has been an increasing demand to use forced air heating and cooling systems that act to recirculate the air inside of the structures. This type of recirculation, while increasing the efficiency of the heating or cooling systems, restricts the turnover of air from the interior to the exterior of the structures. As a result, the air within the structure becomes stale.
To combat this problem, many in the market have turned to solid or liquid aromatic air fresheners, or aerosol air fresheners. However, because their disbursement is restricted, these fresheners are generally limited to the air space in close proximity to them. This reduces their overall effectiveness.
It has been recognized that air freshening is better accomplished by the incorporation of an air freshener inside the air circulation system, since such placement results in distribution of the aromatic throughout the enclosed structure. Several inventions have related to combining into a single product an aromatic material with the air circulation filter. In this respect, see U.S. Pat. No. 4,604,114, wherein the air filter contained solid rods of fragrant scented material embedded in the pad of the filter. See also U.S. Pat. No. 4,118,226, wherein the aromatic is made an integral part of the air filter by banding the aromatic to the perimeter of the filter, and then securing the aromatic with the support casing of the filter; and U.S. Pat. No. 4,065,262 issued to Petroff on Dec. 27, 1977 wherein an air filter combined with a plurality of containers holding a quantity of air freshener composition in the air filter. The containers are selectively opened to allow air flow through them.
These types of air filter-aromatic combinations have presented several difficulties for the air freshener industry. First, by the very nature of the combination, they require the user to purchase these special filter-aromatic combinations in lieu of standard filter types available at most hardware centers. The lack of availability of such filter combinations detracts from the convenience to the end user, and thus from their marketability. In addition, such filter combinations require the user to replace the entire filter "system" when either the aromatic material is spent, or when the useful life of the filter element is at an end, whichever comes first, or when the user wishes to change fragrances. This results in economic waste.
From a manufacturers standpoint, there are other problems presented by prior art practice. First, such combination filters required a manufacturer to greatly multiply his inventory of filtering systems. More specifically, the manufacturer has to multiply the number of filters in each size he desires to keep in stock, by the number of different fragrances he wants to offer to his customers. For example, if a manufacturer wanted to market 4 different aromatic fragrances, he would have to have 4 different filter systems for each size filter. If he made 60 different sizes of filters, which is typical in the air filter industry, he would now have to manufacturer 240 filter systems, instead of 60. In addition, unless the filter combination is sealed in some sort of package, the aromatic will volatize and become unless before it reaches the end user. This packaging, along with the added cost of manufacturing, presents cost barriers that buyers have not been willing to accept.
Other inventions have related to a container that holds an aromatic, and attaches itself to the filter in the air circulation system. In this respect, U.S. Pat. No. 4,563,333, provides an envelope of perforated cardboard with a deodorizing insert is attached to the corner of a filter with adhesive backed tabs. See also U.S. Pat. Nos. 3,902,877 and 4,028,073, wherein a perforated disc shaped container encloses a cake of aromatic material, and attaches itself to one of the circular openings in an air filter.
While such deodorizing devices help to alleviate the problem of offensive odors through the use of an air circulation system, several problems are inherent in their design. First, such devices are generally made out of a material that is not air permeable, i.e., they require perforations to be cut into them to allow for air flow. As a result, their placement onto an air filter reduces the overall efficiency of the heating or cooling system by blocking a portion of the air coming through the system. Second, the placement of such devices is limited to particular areas of the filter, thus reducing the users choice of optimum placement for his air circulation system. Third, the attachment mechanisms are restrictive to certain types of air filters, thus limiting their use in other filtering systems required for other air circulation systems. Fourth, since the installation of the device required some modification to the filter, removal of the device is destructive, requiring replacement of the filter. Fifth, the containers are only capable of storing aromatic material of the solid cake or sheet type. This restricts the choice of aromatic the consumer may desire to use.